Featured Research

from universities, journals, and other organizations

Newly discovered squid pheromone sparks extreme aggression on contact

Date:

February 11, 2011

Source:

Marine Biological Laboratory

Summary:

Scientists have identified a pheromone produced by female squid that triggers immediate and dramatic fighting in male squid that come into contact with it. The aggression-producing pheromone, believed to be the first of its kind discovered in any marine animal, belongs to a family of proteins found in vertebrates, including humans.

Scientists have identified a pheromone produced by female squid that triggers immediate and dramatic fighting in male squid that come into contact with it. The aggression-producing pheromone, believed to be the first of its kind discovered in any marine animal, belongs to a family of proteins found in vertebrates, including humans. Results of the study appear in the February 10th issue of Current Biology.

Related Articles

Male-male aggression is a complex process that involves neural, hormonal, physiological, and psychological stimuli and is widespread in the animal kingdom, where it is associated with the acquisition or retention of shelter and food, and in sexual competition. "The identification of this pheromone as a key component of this signaling system is highly unusual because the male squids need only to come into contact with these protein molecules to initiate the complex cascade of behaviors that we term aggressive fighting," says Roger Hanlon, senior scientist at the Marine Biological Laboratory (MBL) and study co-author.

Squid are highly advanced marine invertebrates with a complex mating system rivaling that of vertebrates. Most mating and egg laying in the longfin squid (Loligo pealeii), the focus of this study, occurs in the spring when the animals migrate from deep offshore waters to shallower waters along the eastern seaboard, from North Carolina to Maine. Females mate multiple times with multiple males, who compete fiercely for females.

In field studies, the scientists observed a visual attraction by male squid to eggs laid on the sea floor followed by an escalation from calm swimming to the highest level of aggressive fighting -- even in the absence of females -- when they physically contacted eggs. Seeking to identify what was triggering the behavior, Hanlon and his colleagues, including Scott Cummins of The University of the Sunshine Coast, Australia, Bernard Degnan of Queensland University, Kendra Buresch of the MBL, Jean Boal and Johanna Holm of Millersville University, and Gregg Nagle of the Medical College of Georgia/University of Georgia Medical Partnership, conducted laboratory experiments at the MBL.

They discovered a protein pheromone produced in the female reproductive tract and embedded in the outer surface of eggs. After purifying the pheromone and presenting it to male squid in the lab, they found the same extreme aggressive responses, even when the protein was "painted" translucently on a glass vial that contained squid eggs. "The contact pheromone was incredibly resistant to degradation," says Nagle. "It appears to remain intact for an extended period of time until the eggs are seen and contacted by male squid."

"Our lab experiments show that the male squid that touches the eggs first becomes aggressive faster than other males who have not yet touched the eggs," says Hanlon. "This leads to dominance by the males that encounter the pheromone. Dominant males pair with the females and mate more often, and they gain greater fertilization success so the extremely competitive aggression has a payoff."

"It was exciting to map an important behavior back to the molecular level," adds Boal. "The research involved careful teamwork among people with very different backgrounds and skills. It was great to be part of such a far-flung and interesting group of scientists."

While there are multiple discoveries of pheromones that can elicit aggression in land-based animals, the scientists maintain that this discovery in squid will help them to understand the critical signaling beneath our oceans. "Squid may have revealed a more direct way of stimulating aggression," says Hanlon. "We doubt that many researchers have thought that contact with molecules in the external world could stimulate such complex and extreme aggressive behavior."

Interestingly, the protein pheromone found in squid has some similarity with beta-microseminoproteins (ß-MSP), a family of proteins found in humans and other animals. "The functions of ß-MSP in vertebrates have not been determined, but our findings in squids may inspire other researchers to consider similar functions in higher vertebrates," says Hanlon.

Mar. 31, 2015 — Using the assessment tool ForWarn, US Forest Service researchers can monitor the growth and development of vegetation that signals winter's end and the awakening of a new growing season. Now these ... full story

Mar. 31, 2015 — Until now electric fences and trenches have proved to be the most effective way of protecting farms and villages from night time raids by hungry elephants. But researchers think they may have come up ... full story

Mar. 31, 2015 — Researchers have detected a human fingerprint deep in the Borneo rainforest in Southeast Asia. Cold winds blowing from the north carry industrial pollutants from East Asia to the equator, with ... full story

Mar. 31, 2015 — A team of engineers and biologists reports new progress in using computer modeling and 3D shape analysis to understand how the unique grasping tails of seahorses evolved. These prehensile tails ... full story

Mar. 31, 2015 — As the five-year anniversary of the explosion of the Deepwater Horizon oil rig approaches, a new report looks at how twenty species of wildlife are faring in the aftermath of the ... full story

Mar. 31, 2015 — Scientists have uncovered the earliest fossilized evidence of an insect caring for its young. The findings push back the earliest direct evidence of insect brood care by more than 50 million years, ... full story

Mar. 31, 2015 — New research has scientists re-thinking how a lethal fungus grows and kills immune cells. The study hints at a new approach to therapy for Candida albicans, one of the most common causes of ... full story

Mar. 31, 2015 — The most virulent strains of Streptococcus suis, the leading cause of bacterial meningitis in adult humans in parts of southeast Asia and in pigs around the world, are likely to have evolved and ... full story

Mar. 31, 2015 — Darwin's evolutionary theory predicts survival of the fittest. So why do different survival tactics co-exist, if evolution should always favor the winning strategy? To answer that question scientists ... full story

Bionic Ants Could Be Tomorrow's Factory Workers

Reuters - Innovations Video Online (Mar. 30, 2015) — Industrious 3D printed bionic ants working together could toil in the factories of the future, says German technology company Festo. The robotic insects cooperate and coordinate their actions and movements to achieve a common aim. Amy Pollock reports.
Video provided by Reuters

Lions Make Surprise Comeback in Gabon

AFP (Mar. 30, 2015) — Lions have made a comeback in southeast Gabon, after disappearing for years, according to live footage from US wildlife organisation Panthera. Duration: 00:32
Video provided by AFP

Related Stories

Feb. 13, 2014 — Female Asian longhorned beetles lure males to their locations by laying down sex-specific pheromone trails on tree surfaces, according to an international team of researchers. The finding could lead ... full story

Dec. 13, 2012 — Scientists have found that male mice produce a pheromone that provokes females and competitor males to remember a preference for the place where the pheromone was previously encountered. The research ... full story

Aug. 9, 2011 — Male squid employ different reproductive strategies depending on their body size. New research shows that the divergent mating behavior of male squid has resulted in the evolution of different sperm ... full story

June 30, 2011 — Pheromone preference, and the initiation of a complex programmed sexual behavior, is determined by the specificity of a single sex pheromone receptor protein expressed in a population of olfactory ... full story

June 30, 2010 — Much like humans, social insects such as ants and bees behave differently when their mother is not around. Workers are thought to perceive the presence of their mother queen using her unique ... full story

ScienceDaily features breaking news and videos about the latest discoveries in health, technology, the environment, and more -- from major news services and leading universities, scientific journals, and research organizations.